Telephone system.



W. MTKEN. TELEPHONE SYSTEM. APPLICATION FILED JULY 18, L9H.

7 lemma Apr. 3,1912:

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TELEPHONE SYSTEM.

APPLICATIUN mm JULY 18. ms

Pateniied Apr 3, 3917'.

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W. AITKENx TELEPHONE SYSTEM.

APPLICATION man IULY 1a. 1913.

, Patent-ed Apr. 3, 1917;

4 SHEETS-SHEET 3 W, AITKEN' HLEPHONE SYSTEM. 7 hPFLiCATiON FILED JULY E8. 1913.

Patented Apr. 3, 1917.

4 SHEETS-SHEE! 4 III-I7 tmrran STATES, PATENT oirsrc WILLIAM AI'IKEN, OF LONDON, ENGLANID.

' TELEPHONE SYSTEM.

M 1 invention relates to common batterv .3

telephone systems and more particularly to common battery telephone systemsiof the manual or semiautomatic type in which cords are used for interconnecting, and has for its objects the giving of the equivalent ofinstantaneous disconnection and the instantaneous making idle of the called and calling lines by either one or both substations replacing the receiver, so that both lines will be instantly available for a call from any other subscriber and either line may instantly, after replacing the receiver or flicking the switch-hook, make a second call'onhis particular line lamp,

My invention will be fully understood from the following description taken in connection with the accompanying drawings which illustrate methods of carrying the invention into effect, and in wh1ch:

Figure 1 illustrates a cord circuit with an e1ectrom'agnetically controlled key to operate in connection with a standard line circuit.

Fig. shows a cord circuit using a relay to perform the same functions as the arrangement shown in Fig. 1. r

. Fig. 3 shows one method of working over a junction line between two exchanges.

Fig. -i shows one form of combined autodisconnection speaking and ringing key.

Fig. 5 shows a cord circuit using a relay as in Fig. 2, but with a modified supervisory system .and circuits differing somewhat and the supervisory means, and

Fig. 6 shows another method of working over "a. junction line between two exchanges,

the supervisory system. differing from that shown in Fig. 3.

Referring .to Fig. 1 a line circuit of a well-known type is shown in which J is an answering jack, J one of a series of multiple jacks, L a calling lamp, 0 a line relay which may have an inductive and a non-inductive winding controlling the lamp L, and A a cut-off relay to open the circuit of the line relay, the winding being in parallel with the meter coil M. At the substation there is Specification of Letters Patent.

Patented Apr. 3, 191%.

Application filed July 18, 1913. Serial No. 779,770.

shown the telephone set comprising a micro phone 1 receiver 2, switch-hook 3, bell 4, and condenser 5 to prevent continuous current flowing through the bell. The cord circuit comprises a disconnecting key K con trolled by the electromagnet D. It will be noticed that all the conductors from the plugs P and P are insulated on the springs G, 7, 8, 9, 10 and 11 normally. The electromagnet D takes the place of the supervisory relay in one conductor of the answering cord P. The key K is linked to a speaking key Q so that when the key Q is pushed forward to connect up the operators telephone circuit comprising a condenser 12, receiver 13 and induction coil 14:, the extension 15 of the key Q causes it to push forward also the lever K to join all the cord conductors through to the associated cord apparatus, and when current passes through the winding D the lever K is heldover by the armature 16. A noninductive resistance 17 is placed in parallel with the winding of the electromagnet D to prevent cutting down of the speech efficiency. The usual meter key 18 is provided to operate the meter M and the meter M. A four wound repeater F with a battery 13 divides the cord circuit into sections for signaling purposes, but allows speech waves to pass freely. 'The usual supervisory relay 19 85 provided when the return of the lever K to the normal position is not considered sufficient, this circuit being controlled by the contacts 21 and 22 and a socket contract 23 controlled by the plug P or by the speaking key aS hereinafter described in connection with Fig. 2. Other details of the cord circuit will be described when considering the operation of the circuit.

Fig. 2 shows a cord circuit in general very similar to that shown in Fig. 1, the main difi'erence being in the use of a relay to controlthe disconnection of the cords instead of a key. Extra contacts 30, 31 and 32 are fittedpn the speaking key Qf of this circuit to control the disconnection supervisory lamp in conjunction ith a relay H.

Fig. 3 illustrates my invention applied to junction working. ,The jack at the outgoing end of the junction is shown at J with the plug P? of an A operators cord equipment. A plug P terminates the incoming junction at another exchange. The new disconnecting relay D is introduced to keep the cord conductors normally open but closed while the junction is in use for a connection. A four wound repeater F is provided with windings and 3+. connected through the condenser and the windings 36 and 37 with the battery B between. A high resistance relay N is connected with its high resistance winding 38 across the condenser 35. The relay N also has a low resistance winding 39 on the same core controlled by the called line supervisory relay 40 in such manner as to give the distant operator full supervision of the connection. The relay T connects up the tertiary winding of the operators circuit for testing purposes and when energized joins the tip conductor of the plug 1 through. The clearing lamp L is under the control of the distant operator by means of the relays N and 41. controls the disconnect relay D. J is a jack of a called line the associated apparatus being similar to that described in connection with Fig. 1. v

Fig. 4 shows one form of combined key for disconnecting, speaking and ringing. Two keys K and Q are fitted on a T shaped section of metal 50, the key K on the left being the disconnect key and that on the right the speaking key. The latter key Q has movement in two directions that toward the straight springs being for ringing and that toward the angled spring for speaking. In taking up this latter position the hand e by the extension 15 forces over the handle or lever K so that the roller K presses the springs 51 and 52 against the springs 6 and 7 respectively. In line with these are two other similar sets of springs making up the combination shown in Fig. 1. The electromagnet I) has two suitably curved pole pieces 53 to engage with the iron roller K when the lever K is pushed to the left. \Vhen the lever Q is returned to the normal or to the ringing positions the lever K does not follow but is retained by the magnet D when energized. and when the circuitof the latter is opened it returns to normal or vertical position which may he sufiicient indication that the plugs may be withdrawn, or this may be supplemented by a lamp signal as already :ucmioned.

The operation of the circuits of the svstem shown in Fig. 1 is as follows: \Vhen the receiver '2 is lifted to make a call a circuit is completed from battery B through the induct'nwinding 00 of relay contacts 61 and 32 of relay A over one side of the line to switch-hook 3, contact 6- receiver 2, mi-

The relay 41 alsr crophone 1, over the other-side of the line,

contacts 05 and 66 of relay-A, non-inductive winding 67 of relay C to the other side-of the battery. The relay 0 completes a circuit through the lamp L, th'rou h contacts 68 and 69 and the lamp glows. he operator answers and learns the callers requirements by inserting plug P in jack J and throwin over key Q which also carries with it key K A circuit is then completed from battery B, resistance 70, contacts 51 and 6 of'key K, sleeve 71, of plug P, bush 72 of jack J, winding of relay A to earth. The relay A energizes and cuts off the line relay (3 and the lamp L ceases to glow. The talking circuit is then as follows: from battery 13, windin 73 of repeater F contacts 74 and 8 of key 1?, tip 75 of plug f, spring 76 at jack J over line and telephone at the callin station as before described to spring 7 7 of ack J, rin 78 of plug P, contacts 7 and 52 of he K winding of electromagnet D with the shunt 17 in parallel with it, winding 79 of re ater to the other side of the battery B. E ectromagnet D is energized and its armature 16 holds the key K so that contacts 51 and 6, 52 and 7, 74 and 8, 80 and 9, 81 and 10, 82 and 11, 21 and 22 are made and retained so long as current passes through the coil D. The operators circuit is completed in the wellknown manner by throwing over key Q throu h contacts and 91 and 92 and 93 of key connecting it across the windings 94 and 95 of repeater F. When' the operator brings the key Q to the through or ringing ositions, key K does not return with it. he plug P is then inserted in the jack of the line wanted corresponding to jack J.

when a circuit is completed from battery B. resistance 96, lamp L, contacts 80 and 9 of key K to sleeve 97 of lug P, then by a circuit corresponding to bush 98'of jack J and winding A to earth. The talking circuit is from battery B, winding 94 of repeater F, contacts 99 and 100 of key Q, contacts 82 and 11 of key K, tip 101 of plug P over the line as already described to ring 102 of plug I, contacts 10 and 81 of key K, contacts 103 and 1(H'of key Q,'relay 19 and winding 95 of re ater F to the other side of the battery B.- he relay 19 by the contacts 105 and 106 shunts out lamp L by resistance 107 when the subscriber answers, the relay-19 not energizing when the plug is first inserted owing to the condenser at the called station keeping the circuit open.

The replacing of the receiver 2 after conversation will open the calling line circuit by introducing a condenser 5 in series with a hell 4. The magnet D will. be de'c nergized and the key K will return to the vertical position to indicate to the operator that the plugs must be withdrawn. The key will open the circuitof all the conductors of the cords so that the relay A will denergim and connect up the line. relay C and bat-- idle. Should the operator be very busy she may delay removing the plugs without the slightest fear of retaining the lines engaged. Should the return of the lever to the vertical position not be considered a sufficient signal, this may be supplemented by a lamp L When the magnet D released, .the key K and contacts 21 and 22 were closed and completed a circuit from battery 13, lamp L contacts and 21 of key K, contacts 110 i and 23 of plug socket contact to earth. The lamp L therefore glows. The plug socket -u ntacts 110 and 23 may be replaced by contacts on the speaking key as will be described hereinafter for Fig. 2. The called subscriber controls the supervisory lamp L in the well known manner, this being shunt-- ed out when the receiver isoif the switchhook and glowing when on the hook.. The operator may cause the meters M and M to register either before or after the receiver is replaced by depressinga key 18, the circuit in the latter case beingfrom battery 13, supplementary battery B, winding of meter M, contacts 111 and 112 of key 18, sleeve 71 of plug P, bush 72 of jack J, winding of relay A and winding 112 of meter iii in parallel to earth. The meter M registers after the meter M, when the resistance otthe circuit has been reduced by the'arinature of M bringing in the front winding 113.

Referring to Fig. 2, the cord circuit shown therein operates generally in a manner ery similar to that shown in Fig. 1. lVhen the operator inserts a plug P and pushes over key Q (to the left with reference to Fig. 4) to answer a call, the circuit is completed from battery 13, winding 120 of magnet D ':ontacts 31 and 30 of key Q to earth. The

magnet I isenergized and closes all these (ilhtilctsh normal or ringing positions the magnet D is retained energized because a circuit is completed from battery 13*, winding 121 of repeater F contacts 122 and 123 of magnet I); tip 121- of p ug P over a circuit described in connection with Fig. 1, back to the ring125 of the plug P contacts 126 manner, a circuit being completed from the and 127 of the magnet D winding 128 of I'uagnet D with shunt 129 inparallel withit to the winding 130, repeater F to the other side of the battery B. l/Vhen the receiver at the calling station is replaced and the circuit opening'the magnet D insulates When the key Q, is returned to all cord conductors and therefore allo\ vs"the line relayand lamp to come into circuit and,

also removesthe en'gaging current from the test circuit of the nultiple Jacks. When the plug P is in the jack, the third,conductor;

circuit is as follows, from battery lfi, relay H} contacts 131 and 132 of magnet D, sleeve 13%? "of plug P, bush of corresponding jack,

and the cut-off relay to earth. The relay H .is energized and completes a circuit through contacts 134 and 135 of relay H, lamp L springs 32 and 30 of key Qpto' earth. The lamp L is shunted out by the winding of the cut-off relay but when the replaced receiver causes the magnet D? to open all the circuits, the relay H remains energized and the lamp L glows as a clearing signal. The lamp L glowing will indicate idle lines and will either glow until the. plugs are brought into use for anotherv connection, or the operator may 'flick over the key Q to momentarily open thecircuit. These contacts may be made at the plug socket as described in connection with Fig. 1. Referring to Fig. 3 the invention is shown applied tojunction working. When a call is answered as described in connection with Figs 1 and 2 andthe line wanted is in another exchange the A operator will pass the call to a B operator in theexchange in which the called line is located, and that operator will allocate the junction line. The A operator will insert the plug P in an out-going junction jack J 2 when the circuit will be eX- tended from tip 140 of plug P to spring 141 of ack J over the line to the distant ex-. change, winding 33 of repeater F, high re? sistance winding-38 of relay N, winding'34 of'repeater F, over the other side of the line to spring 142 of jack J 2 and ring 143 of plug P The relay N will be energized and complete a circuit from earth, contact-dl144 and. 145 of relay N, winding of relay 41 to battery B to earth. The relay 41in turn will complete a circuit from earth, contacts 146 and 147 of relay 41 winding of relay D to battery B and earth. The relay D will complete circuits when the plug P is in j ack J as follows: from battery B, winding 36 of repeater F, contacts 148 and 149 of relay D, contacts 150 and 151 of magnet T,

tip 152 of plug P and over the line circuit I multi led test wire of the line to be connected to by bush of jack 160, tip of plug '152, spring 150 and back contact of relay T, tertiary winding IO of operators induction coil to earth.

When the plug P is inserted in jack J a third conductor circuit is completed from battery B magnet T, lamp L, contacts 157 and 158 of relay 1)", sleeve 159 of plug 1, bush 160 of jack J and winding of relay A to earth. As the relay 41 is energized the lamp L is slmnted out by the resistance 161 and contacts 16:. and 163 of relay 41. The

relay 40 is energized when the receiver is lifted :Iid completes by its contacts a circuit through the low resistance winding 39 of relay N in parallel with the high resistance winding 38, so that the supervisory relay 19 (Fig. 1) is energized, and shunts out the lamp L and the A operator thus knows that the called subscriber has answered.

When the calling subscriber replaces the receiver after conversation the magnet D de-v energizing allows the key K to open all its contacts and thus insulating all the conductors of the plug 1. The relay N is deenergized and its local circuit opens the circuit of relay 41 which opens the circuit of relay D which insulates all conductors of the plugs P (Fig. 3) and thus removes the busy test from the multiple jacks and allows the line relay C to join up the line lamp L". The relay 41 also removes the shunt from the lamp L so that it glows as a clearing signal, its circuit being from battery B relay T, lamp L, contacts 158 and 164 of relay D', contacts 165 and 166 of socket contact to earth. hen the plug P is returned to its socket the lamp ceases to glow. Instantaneous withdrawal is not however essential and the hop L glowing may be taken as a signal that the line is now available for another connection, so that glowing lamps will indicate idlelines. The lines in both exchanges for all practical purposes have been automatically disconnected and.

restored to normal or calling condition. and

.rhaps of greater importance the auction ine has been made available for immediate further use, instead of waiting the pleasure or leisure of the A operator to withdraw the plugs at her position as at present.

The called subscriber by replacing his receiver decnergizes the relay 40 (Fig. which removes the slnmt winding of relay N so that the relay 19 (Fig. 1) opens the shunt about the lamp L and allows it to glow.

In the specific forms of the invention hereinbefore described supervisory lamp signals have been provided which are caused to glow on the termination of the period of connection. There will now be described arrangements in which a lamp is caused to glow during the period of connection and to be extinguished'at the termination of the connection, that is to say, when the plugs become electrically inoperative.

In Fig. 5 a cord circuit is shown similar inoperative by means of a relay D. L is the supervisory lamp which glows during the period of connection and is extinguished at the termination of the connection. Q is the combined speaking and ringing key, with the slmaking part of which magnet D is linked electrically so that when the operator moves the lever to connect her speaking set to answer a call, relay I) is energized over the subscribers line. For this purpose the relay 1). has three windings, two with battery between being joined across the loop and the other being joined to a contact on the speaking key, the three windings mag netizing the core in the same direction. The lamp L has its circuit completed through contacts on relay D"so that it glows so long as relay 1) is energized. The lam L is controlled by the relay 170. The re ay 170 is double wound with battery connected between the windings and it is connected across the calling cord for supervision purposes and through the windings current is supplied to the called subscriber-s microphone. M is the operators meter controlled by the key 171:

It will be seen that the cord circuit in Fig. 5 is arranged on the well-known Stone system with condensers to divide the cord circuit as distinguished from the arrangement shown in Fig. 2 where repeater coils are employed.

The operating and the circuits are described in detail hereinafter.

Fig. 6 illustrates another method of applying the invention to working over a junction line between two exchanges. As in the arrangement shown in Fig. 5 aisupervisory lamp (lamp L") is caused toglowduring the eriOd of connection andis'lextinguished at the termination pf thecon-n ection. The supervisory lamp L" is controlled directly by the relay 1) and this arrangement makes it possible to simplify the circuits considerably.

' The supervisory relay 0 isshown joined in parallel with'the repeater.

The operation of the arrangement shown in Fig. 5 will now be described. i To answer a call the plug 1 is inserted in a jack such as the jack J in Fig. 1 and the speaking key lever pressed back so that contacts 17:2 and 173, 174 and 175 are closed and the operators telephone set joined across the cord. At the same time-contacts 176 and 178 ,of the key Q are closed completing a local circuit from battery B, winding 179 of relay D", contacts 178 and 176 of key Q-'- to earth so that relay I) is energized and joins all of the conductors through so that circuits are completed from plug 1 to plug-P. The calling lamp ceases to glow as the cut-ofi' relay is energized owing to a circuit being completed from battery B, rfiistanoe 180,

contacts 181 and 182 ofrelay-D to sleeve 183 of plug P bush of the jack and winding" of cut-off relay to earth. 1

A circuit is completed over the calling line from battery B, winding 184 of relay D contacts 185 and 186 of relay D tip 187 of plug P to onespring of the jack over the line wire throu h the subscribers s)eakin 5 set and backby the otherline wire to the other spring of the jack, ring 188 of plug P contacts 189 and 190 of relay D winding 191 of relay D to earth. One side of each of the windings 184: and 191 are connected also to the condensers 192 and'l93 so that speech may be transmitted. The operators microphone is in a local circuit (not shown) of the coil 194: with battery.

Having. learned the callers requirements the operator tests the line wanted by touch: ing the jack of the called-linewith the tip of the plug P in the well-known manner and if the lineflis idle inserts the plug P when circuits similar to those just described are completed for the called line by contacts 195' and 196 and 197 and 198 of relay D". Current is fed through windings 199 and. 200 ofrelay 170. The cut-off relay is energized from .a circuit from battery B", lamp L contacts 201 and 202 of relay 170, contacts 203 and 204 of relay D sleeve 205 of plug P, bush of jack, winding of cut0fi' relay to earth. The lamp L glows until the subscriber answers, when the relay'170 is energized and the lamp circuit broken, it being replaced by the resistance 207. After inserting the plug P in the jack ofthe called line the operatormoves the lever of key Q to the ringing position and thereby breaks the circuit of the winding 17 9 of the relay D and this relay is now already energized by the circuit through the callers speaking set. It now the caller replaces his receiver, the circuit will be opened and the relay D denergized so that it opens the circuit-of all the conductors. The lamps L glowing during the period of a connection may be used as an indication of the operators load to the supervisor who can then,?

more readily than with'the systems at present in use, take steps for equalizingthe load. The called line is safeguarded against the caller holding up his line by refraining to replace the receiver promptly as the party calling causes the supervlsory lamp L to glow, in these circumstances.

The operation of the arrangement shown in Fig. 6 is as-follows: The A-operathr whom it will be assumed, for convenience is provided with cord circuits shown. in Fig. 5, desiring a connection in another exchange asks for it over an order wire and is allotted a junction by the Ev-operator. The A operator inserts the plug 1 .(similar to plug P". of Fig. 5) in the jack J; thereby jacks of the line and the supplying battery through windings 2-10 and 55 to earth. Relay Dis energized and oins all the conductors through to the plug P and also completes the circuit from battery B 'through the lalnpL, contacts 215 and 216 of relay D" to earth, so that the lampL glows and remains glowing so long-as the 7 plug P is in the jack J and the calling subscriber has not replaced his receiver on the hook. i

The B-operator tests the line wanted and if idle inserts. the plug P into thejack of 3 the called line when the induction coil winding 217 of her testing circuit is opened and the tip conductor circuit completed by the action of the third conductor relay 218 in the well-known manner, the circuit to the plug 3 sleevev 219 being completed by contacts '220 and 221 of-rel'ay Dt. Current is supplied to the called line from battery B 'windings 222 answers, relay 0 is energized and a circuit completed for the low resistance winding 9 228 of relay R-in parallel with the *high resistance winding 212. The loweringof the resistance over the junction line causes the supervisory relay of the A operators cord to be operatively energized, thereby opening the circuit of the supervisory lamp. For example, with the A operators cord circuitshown in Fig. 5, the relay 170 is energized, opening the circuit of the lamp L 1.

After conversation, when the callinglines speaking set is put out of circuit, relay D (Fig. 5) is deenergized and opens all the plug conductor circuits. Relay R isthusf denergized and opens the circuit of relay D and it in turn opens the circuits of the plug P so that the engaging batteryisflremoved from the multipled bushes of the line tests instantly idle to another operator.- The cut-oil" relay is also released so that the line lamp-isin circuit to indicate another call if the receiver is again lifted, and the'plug is inoperative and may remain in the jack until required for another connection. The lamp L ceasingito low indicates that the plug is now'avail'able for further use. The replacing of the" receiver of the calling party thus automatically releases the two lines connected, and restores them to their normal orcalling condition and also releases instantly the junction cir- 1 if the called line receiver is replaced in this condition the relay 0 opening the shunt circuit, the relay 170 (Fig. 5) at the A position, will deenergize and the lamp therefore will glow, indicating this irregularity. The lamps L glowing during connection will indicate to the supervisor the nature of the traffic and the suitability of the junctions provided for the amount of traflic, and they can therefore be loaded to their maximum capacity more efficiently without interfer-- ing with the efliciency of the service.

In the foregoing description of the invention as applied to working over a junction line between two exchanges it has been assumed in the case of the arrangement shown in Fig. 3 that the A operator is provided with cords similar to that shown in Fig. 2 and in the case of the arrangement shown in Fig. 6 that the A operator is provided with cords similar to that shown in Fig. 5, but this is not a necessity as the invention can be applied to junction working with any type of cord at the A opcrators position.

Various modifications may be made in the method of carrying this invention into efl'ect, the above as applied to manually operated switchboards being given merely by way of example.

For example the invention is applicable to all known common battery circuits whether using repeaters, coils, condensers and relays with or without retardation coils and the like.

Further it will be readily understood by thoseskilled in the art that the invention can be advantageously applied to semi-automatic switchboards, non-multiple private bank branch boards where the same cords are used for working between two local lines or a local,line to a junction or the like.

\Vhat I claim and desireto secure by Letters Patent is V 1. In a common battery telephone or like system, the combination of a calling line, :1 called line, an operators cord circuit for effecting or completing connection between said calling line and said called line, a plug for said cord circuit and means foropening the conductors connected to said plug to break down the connection and to restore the lines to normal condition upon the talking set of one of the lines being disconnected from said line, all of the circuits of the cord being returned to normal without further operating act.

:2. In a common battery telephone or like system, the combination of a calling line, a called'line, an operators cord circuit for effecting or completing connection between said calling line and said called line, for said cord circuit and means for automatically opening the conductors connected to said plug to break down the connection a plug and to i'estore the lines to normal condition upon the talking set of one of the lines being disconnected from said line, all of the'circuits of the cord being returned to normal without further operating act.

. 3. In a common battery telephone or like system, the combination of a calling line a 5 called line, an operators cord circuit or effecting or completing connection between said calling line and said called line, a plug for said cord circuit, conductors in said cord circuit connected to said plug and to springs, 0

and electromagnetic means for separating said springs to.open the connection to said plug to break dOWl'ttllB connection and to restore the lines to normal condition upon the talking set of one of the lines being disconnected from said line, all of the circuits of the cord being returned to normal without further operating act.

5. In a common battery telephone or like system, the combination of a calling line a 00 called line effecting or completing connect-ion between said calling line and said called line, a plug for said cord circuit, conductors in Said cord circuit connected to said and electromagnetic means for separating said springs to open the, connection to said plug to break down the connection and to restore the lines to normal condition upon an operators cord circuit tor 1 plug and to springs the talking set of the calling line being disconnected from said calling line, all of the circuits of the cord being returned to normal without further operating act.

6. In a common battery telephone or like system, the combination of a calling line. a 110 called line, an operators cord circuit for effecting or completing connection between said calling line and said called line, a plug for said cord circuit, a relay. conductors in said cord connected to contacts on said relay l20 and means for automatically operating said relay to open the connection to said plug to break downthe connection and to restore the lines to normal condition upon the talking set of one of the lines being disconnected from said line,

being returned operating act.

7. In a common battery telephone or like all of the circuits of the cord to normal without further system, the combination of a calling line. a

called line, an operators cord circuit for effecting or completing connection between said. calling line and said called'line, a plug from said calling line, allot-the circuits of thecord being returned to normal without further operating act. 1 8. In a common battery telephone or like system, the combination of a calling line, a

called line, an operators cord circuit-for effecting or completing connection between said calling line and said called line, aplug for said cord circuit and means for opening the conductors connected to said plug upon the talking set of one of the lines being disconnected from said line,'the connection to said plug being normally open.

9. In a common battery telephone or like system, the combination of a calling line, a called line, an operators cord circuit for effecting or completing connection between said calling line and said called line, a plug for said cord circuit and means for automatically opening the conductors connected to said plug upon the talking set of one of the lines being disconnected from said line, the connection to the said plug being normally open.

10. In a common battery telephone or like system, the combination of a calling line, a called line, an operators cord circuit for effecting or completingconnection between said calling line and said called line, a plug for said cord circuit and means for automatically opening the conductors connected to said plug upon the talking set of the calling line being disconnected from said calling line, the connection to said plug being normally open,

11. In a common battery telephone or like system, the combination of a calling line, a called line, an operators cord circuit for effecting or completing connection between said calling line and said called.line, a plug for said cord circuit, conductors in said cord circuitzconnected to said plug and to springs, and electromagnetic means for separating said springs to open the connection to said plug upon the tal ing set of one of the lines being disconnected from said line, the-com nection to said plug being normally open.

12. In a common battery telephone or like system, the combination of a calling line, a walled line, an operators cord circuit for effecting or completing connection between said calling line' and said called line, a plug for said cord circuit, conductors in said cord circuit connected to said plug and to springs and electromagnetic means for separating said springs to open the connection to said plug upon the talkin set of the calling line being disconnected trom said calling line, the connection to said plugbeing normally open., i

13. In a common battery telephone or like system, the combination of a calling line, a called line, an operators cord circuit for effecting or completing connection between said calling line and said called line, a plug for said cord circuit, a relay, conductors in said cord connected to contacts on said relay and means for automatically operating said relay to open the connection'to said plug upon the talking set of one of the lines being disconnected from said line, the connection to said plug being normally open.

let. In a common battery telephone or like system, the combination of a calling line, a

called line, an operators cord circuit foreffecting or completing connection between said calling line and said called line, a plug for said cord circuit, a relay, conductors in said cord connected to contacts on said relay and means for automatically operatingsaid relay to open the connection to said plug upon the talking set of the calling line being disconnected from said calling line, the connection to said plug being normally open.

15. In a common battery telephone or like system, the combination of a calling line, a. called line, an operators cord circuit for effecting or completing connection between said calling line and said called line, a plug for said cord circuit, means for automatically opening the conductors connected to said plug to break down the connection and to restore the lines to normal condition upon the talking Set of one of the lines being disconnected from said line, all of the circuits of. the cord bcin-g returned to normal without further operating act, and means for gfllng a supervisory signal when the connection through to the plug is broken.

16. Ina common battery telephone or like system, the combination of a calling line, a

called line, an operators cord circuit for eff'ecting or completingconnection between said calling line and said called line, a plug for said cord circuit, means for automatically opening the conductors connected to said plug to break down the connection and to restore the lines to normal condition upon the talking set of the calling line being disconnected; from said calling line, all of the vii'cuit. an operators key associated with sand cord cn'cmt, a plug for smd cord clrcult, vomlm'turs 1n said cord clrcuit connected to said plug, and normally open in said cord. wuuit, means for'nutomatically closing said Conductors in said cord circuit on the operation of said key to connect the operators tniicing sex in circuit, and means for opening the conductors connected to said plug upon the talking set of one of the lines being (iia- 10 connected from said line.

In testil pony whereof I have fixed my signature 1n presence of two witnemes.

WILLIAM AITKEN. Witnesses:

WILLIAM S. Comma, H. D. Jnxnsox. 

